1. Field Of The Invention
This invention relates to an endodontic post construction for use in anchoring a tooth restoration to a portion of an injured tooth.
2. Description Of The Prior Art
When repairing severely damaged teeth, a dental post or endodontic post is often utilized to help anchor a tooth restoration such as an artificial crown to a remaining root portion of a tooth. For example, the crown may be broken from a tooth by a traumatic injury or may have substantial portions thereof removed due to removal of decayed areas, thus leaving the root or roots of the tooth along with a relatively short stub of the original crown extending above the patient's gum area.
When the damage to the tooth is such that it is necessary to remove the pulp material from the root canals, it is common to use an endodontic post to help anchor the artificial crown to the remaining original tooth structure. An endodontic post is a cylindrical pin which is cemented into the endodontically prepared root canal and extends above the surface of the remaining natural tooth to serve as an anchor for the artificial crown restoration which is attached to the remaining natural tooth.
In multi-canaled teeth such as molars, there will typically be two such posts, one placed in each of two separate canals. In single-canaled teeth, typically a single cylindrical post will be placed in the canal.
A general description of these prior art procedures utilizing endodontic posts, both in multi-canaled and single-canaled teeth is provided in "Preparing Severely Damaged Teeth", March, 1983, CDA Journal, pages 85-91 by Shillingburg, Jr., et al.
The posts utilized for such tooth restorations are typically cylindrical, often having grooves, threads or flutes formed in the post for aiding in cementing the post in place and/or venting cement from the root canal as the post is placed in the canal.
One typical prior art construction for such a post is that shown in FIG. 1 of U.S. Pat. No. 4,479,783 to Weissman. The post shown in FIG. 1 of Weissman has a spiral groove or thread 18 cut therein at a very large pitch angle to the longitudinal axis of the post. The pitch of the spiral groove is so great that it cannot effectively function as a vent. A longitudinally extending vent 24 is provided.
FIGS. 2 and 3 of U.S. Pat. No. 4,479,783 to Weissman disclose another helically fluted dental post which has a plurality of grooves placed at a very shallow (approximately 7.degree.) pitch angle. The shallow spiral flutes of FIGS. 2 and 3 of the Weissman '783 patent function as vents, and additionally to help retain the post in place once it is cemented within a prepared root canal.
Other disclosures similar to that of FIGS. 2 and 3 of Weissman U.S. Pat. No. 4,479,783 are found in U.S. Pat. Nos. 4,729,736; 4,708,655; and 4,600,392, all also to Weissman.
U.S. Pat. No. 4,268,253 to Gross et al., discloses an endodontic post having a generally polygonal cross section which has been twisted to form a plurality of side-by-side vent grooves. The outer surface of the Gross et al. post is substantially completely covered with grooves and there is no significant non-grooved portion.
U.S. Pat. No. 4,276,027 to Lustig and U.S. Pat. No. 4,490,116 to Deutsch et al., both show endodontic posts having straight longitudinal vent grooves.